1. Field of the Invention.
The present invention pertains to furniture, and more particularly to chairs having vertically adjustable backrests.
2. Description of the Prior Art.
It is well known that office furniture designed to human engineering standards increases worker efficiency and productivity. Properly designed chairs are especially important, because office workers spend considerable portions of the work day seated at their work stations. Chairs that reduce or eliminate fatigue and backache are therefore critical to the modern office.
Various types of specialty office seating has been designed to enhance worker comfort and effectiveness. One common specialty chair is the secretarial chair, which is especially useful for typists and computer operators. Secretarial chairs have distinct and separate backrests and seat portions. The seat height is usually adjustable with respect to the floor, and the forward and backward distance of the backrest relative to the seat portion is also usually adjustable. The backrest normally is tiltable about a transverse horizontal axis.
A major handicap of prior secretarial chairs is the lack of easy vertical adjustment of the backrest relative to the seat. Backrest height adjustment is very important for proper support of the person's back, which is essential for comfort and productivity. It is highly desirable that backrest adjustment be accomplished with the person seated in the chair, so as to eliminate repetitive and wasteful trial and error adjustments. Ease of vertical adjustment makes it practical for different workers to use the same chair, and also to allow a new chair to be quickly put into use.